Doctor John H Watson: Consulting Detective
by therunawaypen
Summary: Detective Inspector Sherlock Holmes is at his wits end trying to solve a string of "serial suicides" when his old mentor Greg Lestrade suggests he seek the input of one Doctor John H. Watson. Reversal of "A Study in Pink" with John as the genius and Sherlock as the poor sap who gets dragged along for the ride. SLASH pre-Johnlock, Mystrade
1. Chapter 1

_I've been wanting to write something like this for a while, since there are not nearly enough of these fics. A big thanks to harlieford on Tumblr for the prompt!_

* * *

The scene was just like the others. Victim choked on her own vomit, no signs of struggle, in a place she wasn't likely to be found, a bottle of pills by her side.

All evidence pointed to suicide.

Just like all the others.

"There's no such thing as serial suicides…" Detective Inspector Holmes muttered, rubbing his weary eyes. He held his cell phone to his ear, pacing the area outside the crime scene, "This is the third one…"

On the other end of the line, DI Lestrade sighed, "_Yeah, I know Sherlock…"_

"We're _missing_ something!" Sherlock hissed, running a hand through his curls, "I just can't _see_ it…"

It wasn't the first time Sherlock called Greg while he was at t a crime scene. When Sherlock had first started at New Scotland Yard, he had been assigned to work under Lestrade. The two eventually became partners before Sherlock was given his own team. But the younger man still called his mentor. The two DIs were usually able to talk each other through their respective crime scenes.

Lestrade was also one of the few people Sherlock trusted with his insecurities. Or think less of Sherlock for his…history.

"_You'll find it, Sherlock."_ There was shuffling on Lestrade's end of the line. Most likely catching up on paperwork before heading home. "_You'll find the missing piece."_

"I should have found it after the second victim!" Sherlock grit his teeth, "I need your help, Greg."

There was a long pause while Sherlock waited for Greg to respond.

"…_I think I know somebody."_

* * *

"A doctor, Greg?" Sherlock raised an eyebrow as he followed Lestrade through the halls of Saint Barts.

Greg nodded, "Yeah, I know it's crazy, but trust me, Sherlock. You remember the triple murder last year we thought was the result of Satanists?"

"Yes…" Sherlock answered hesitantly. That case _still_ gave him the creeps, even if he hadn't been the one working it.

Lestrade sighed, hands in the pockets of his jacket, "Yeah, well, this guy helped us close the case."

_That_ caught Sherlock's attention. Greg didn't like letting civilians in on cases. "What's so special about him?"

"In short? He's a genius." He admitted, opening the door to a lab.

Sherlock snorted as followed his old partner into the medical lab. It did seem ludicrous, but it wasn't often that Lestrade admitted the strength of others (especially if it made him look bad).

There were two people in the lab, working quietly. There was a petite brunette woman walking across the lab with two cups of coffee, "Here's your coffee, John." She said quietly, setting a cup on a counter.

The other doctor, John, didn't look up from his work (a human brain, from the looks of things). Instead, he picked up the cup with a (bloody) gloved hand, sipping it while he poked around the brain.

Sherlock looked at Greg, raising an incredulous eyebrow. At Greg's nod that, _yes, that_ was the doctor they would be talking to, he couldn't help but rub the crook of his arm. The whole situation was setting Sherlock on edge, and it made Sherlock long for his old needle and cocaine.

But after being unable to solve the riddle behind three serial suicides, Sherlock was willing to try anything.

"You should get some coffee for our guests, Molly." The doctor spoke again, setting down his scalpel.

The female doctor, Molly, looked over at Greg and Sherlock. "Oh, um…"

Lestrade shook his head, "None for me, thank you."

Sherlock cleared his throat, rubbing his arm again, "Black, two sugars, if you don't mind."

Molly smiled softly, "No problem." She replied before heading to another room.

The remaining doctor finally looked their direction, giving Sherlock the opportunity to take in the other man's appearance. He was the shorter side as far as men were concerned, but his posture commanded authority. His blonde hair was kept short and neatly styled, and underneath the white labcoat, he was just as well put together. Sherlock could see a deep purple dress shirt stretched across the doctor's sturdy frame, tucked into a pair of black slacks. And while Sherlock wasn't much for fine clothes (too much time around Mycroft during their childhood), he could recognize the elegant shoes the doctor wore as he approached them.

"I need your phone, Lestrade. Mine has no service down here." He said smoothly, his voice light and polite.

"What's wrong with the landline?" Lestrade asked, raising his eyebrow.

"I prefer to text." The doctor chuckled, "And you should use more lubricant next time you're intimate with your lover."

Sherlock looked at Lestrade, horrified at the implication. While he was more than aware that Lestrade and his brother had been in a committed relationship for years, he did _not_ need reminding of the things they got up to in their bedroom.

Lestrade grimaced, "And how—"

"Your limp. Now, your phone?"

Greg patted his jacket pockets, sighing, "I think I left it in my car."

Sherlock cleared his throat, "Here, use mine." He said softly, handing over his phone.

Lestrade nodded to Sherlock, "This is an old friend of mine, Sherlock Holmes."

The doctor took Sherlock's phone without acknowledging Greg, tapping out a text message with quick thumbs, "So, how long have you been clean?"

That made the young detective blink, "E-excuse me?"

"I didn't realize I had stuttered." The doctor muttered, "I said 'how long have you been clean?"

Sherlock was briefly saved from answering by Molly returning with coffee. She smiled warmly at him when he muttered his thanks, staring deep into the black liquid. "How did you—?"

John smirked, not looking up from the phone, "You were rubbing the crook of your arm when you first came in. You were agitated and desiring a hit, but it's been a while. And since it was an intravenous drug, that would leave cocaine, heroin, or morphine. And considering the fact you do not have the medical means to obtain morphine, nor do you look strung out enough to have been dependent on heroin, that would leave cocaine. But you've kicked the habit, otherwise you would not still be working at Scotland Yard. So, the question remains, how long have you been clean?"

Lestrade gave Sherlock a look, a reassuring one. Sherlock cleared his throat again, trying to regain his bearings, "Nine months…since I left rehab."

The doctor nodded, "Wonderful, I wouldn't want to room with a junkie."

"Excuse me?" Sherlock blinked. They were here for a case, who said anything about rooming? He looked at Lestrade, "Did you tell him about me?"

Greg shook his head, "Absolutely not."

Doctor John, for want of a better name, was not listening. He was hanging up his lab coat on a hanger by the door, "There's a lovely place in central London we can afford together. Unless of course you want to continue to sleep on your brother's couch."

Sherlock was so stunned, he couldn't think of anything to say while the doctor slipped on a long black coat and adjusted his scarf.

"Leaving so soon John?" Molly asked, breaking Sherlock from his daze.

"Of course, Molly. I left my riding crop in the morgue." He smirked.

It was then Sherlock found his voice, "Hold on! I came here about a case, not to find a flatmate."

"I know that. It's the only reason Lestrade ever contacts me." The doctor chuckled. "Flatmate and a case, it must be my birthday. We'll meet at 7, yes?"

"No!" Sherlock shook his head, "We don't even know each other!"

"Wrong. I know everything about you."

"I don't know you!" Sherlock was getting flustered, "I don't know where we're supposedly meeting, and I don't even know you're name!"

"Yes you do, you heard Molly say it just now." John smirked again, slipping on a pair of black gloves. "But if it puts you at ease, the name is Dr. John H. Watson. And the address is 221b Baker Street. Remember, 7pm and try not to forget the case files."

With that, Doctor Watson left the lab in a whirl of his coat.

Sherlock looked back at Lestrade, who nodded, "Yeah, he's always like that. He likes you."

"Because he asked me to move in with him?"

"He hasn't insulted you yet."

* * *

_I hope you enjoyed! Let me know what you like to see next!_


	2. Chapter 2

_So I couldn't help myself, I just had to continue! At least for "A Study in Pink"_

_I'm taking some liberties with both the characters and the plot, to make things fit a bit better with John and Sherlock's new roles. I had them keep some traits about themselves in their new roles to change the dynamic. Otherwise, it would just be the same thing, just with John reading Sherlock's lines and vice versa._

_Anywhoo, I hope you enjoy this chapter! It's kinda an interlude and building on Sherlock and John's introduction/relationship._

* * *

_It has been almost a year (11 months, 2 weeks and a day) since my last high, and nine of those months have been outside a rehabilitation facility. The stress and pressure at work today made me long for another hit, but someone alerted me to my previous addiction, reminding me _why_ I quit in the first place. I met—_

"So I heard you met Dr. Frankenstein."

Sherlock looked up quickly, closing out the window to his personal blog. Just because he kept record of his journey after rehab didn't mean he wanted anyone _else_ to read it. But it was just Dimmock, Lestrade's current partner, standing on the other side of his desk. To Sherlock's embarrassment, he could never remember the DI's first name, he just always called him "Dimmock," hoping that his first name would be mentioned in a conversation at some point.

"I'm sorry?" Sherlock blinked, gathering his thoughts.

Dimmock shook his head, "Watson. I heard you and Lestrade paid him a visit for the serial suicide case." He snorted, "He's a piece of work, that one."

Sherlock chuckled, "I've certainly never met anyone like him before."

"Thank God for small blessing, yeah?" The other DI chuckled, hands in his pockets, "I keep telling Lestrade not to keep calling that guy, but I think Watson has some sort of blackmail on Lestrade."

While it sounded like a feasible explanation as to why a civilian doctor would be allowed to consult on Lestrade's cases, Sherlock knew it wasn't true. Simply put, if Lestrade was being blackmailed by _anyone_, Mycroft would have put a stop to it. Mycroft was insanely possessive that way.

"Well I'm meeting with him tonight to discuss the case." Sherlock nodded, "Hopefully a pair of fresh eyes will at least turn up some new ideas."

Dimmock nodded, "Just be careful. There's something not right with that one."

Sherlock only nodded as Dimmock returned to his own desk to work. Making sure he wouldn't get any more visitors, Sherlock reopened his blog

_I met a doctor today. He—_

Sherlock paused in his typing. What could he write about Doctor Watson, other than the fact he was either insane or a genius. Already, he was fighting the urge to rub his arm again.

Quickly, he opened a new tab on his browser, typing in the search bar: _Doctor John H. Watson._

* * *

"I can't believe I'm doing this…" Sherlock mumbled to himself, clutching the case file in his hand tightly as he looked up at the door in front of him.

The numbers on the door in front were unassuming "221B," and the door itself was situated next to a small sandwich bar and café. It certainly didn't look like the type of place a genius doctor would be living.

A genius doctor. Sherlock wouldn't have believed it if he hadn't seen it himself. He was still trying to figure out just how Doc. Watson had known everything about him. Part of him still thought that perhaps Lestrade had tipped the doctor off about some aspects of his personal life (though, deep down, he knew Lestrade better than that).

Another part was desperately hoping that the doctorwas just as bright as he seemed, that he could help solve this mystery on Sherlock's hands.

"Ah, there you are Mr. Holmes. Right on time, lovely."

Sherlock blinked, turning from the door to see Dr. Watson walking towards him. "Good to see you again, Doctor Watson."

"John, please."

"Then call me Sherlock."

The doctor smirked, "I intend to." He chuckled, ringing the bell next to the door, "The landlady, Mrs. Hudson, is giving us a great deal. I met her while I was on holiday in Florida and she owes me a favor after I helped with a case after her husband landed himself on Death Row."

Sherlock blinked, "You actually helped her husband get off Death Row?"

John looked back at him, chuckling lightly, "Of course not. That was the point."

Before Sherlock could reply, the door opened revealing a petite woman who appeared to be in her early 60's.

"John!" She beamed, hugging the doctor tightly.

"Hello, Mrs. Hudson" John kissed her cheek lightly, "It has been too long, hasn't it?"

"Too long indeed." She smiled, "Oh and who is this?" She was looking at Sherlock now.

Before Sherlock could open his mouth to answer, John butted in, "This is Sherlock Holmes, the flatmate I told you about."

"No, wait! I'm not here—"

"Oh wonderful!" Mrs. Hudson clapped her hands excitedly, "Come in, come in!"

For such a small women, Mrs. Hudson had a surprisingly strong grip as she grabbed Sherlock's wrist and dragged him up the stairs, John following behind.

Despite his insistence that he was _not_ there to become John's flatmate, Sherlock had to admit the flat _was_ a good deal. It was very neat and tidy, at least one half was. The other half was completely bare.

"I take it you moved in already?" Sherlock looked at John, fingers tapping a book on Anatomy that was laying on the coffee table.

John chuckled, "Yes, I didn't see the point in wasting time. I left the other half open for you to move your things in."

"There's a second bedroom upstairs, love." Mrs. Hudson nodded, smiling happily, "If you'll be needing two."

Sherlock blinked, "Why wouldn't we need two bedrooms?"

Mrs. Hudson pat his arm gently, "Oh don't you worry, dear, we get all sorts here. Mrs. Turner next door, she's got _married ones_." She was nodding conspiratorially.

_That _made Sherlock blush. "No! You're mistaken, I'm not gay!"

John chuckled lightly, "He'll take the second bedroom, Mrs. Hudson."

Sherlock opened his mouth to argue that he was _not_ there to flatshare as Mrs. Hudson made her way back to her own apartment, but stopped himself. "…There's really no sense in arguing, is there?"

"Not really, no." John was making himself comfortable in an armchair by the fireplace.

There was a moment Sherlock just watched the doctor make himself at home in the cozy little flat, "So that's it then? We just met, and we're going to share a flat? We hardly know each other."

John rolled his eyes, "As I told you at the lab, I know just about everything about you, Sherlock."

"Knowing that I used to do cocaine does _not_ mean you know me!" Sherlock snapped, gripping his case file tightly, "Nor does it mean I'm a good flatmate."

"I tend to exercise when I'm thinking, sometimes in the middle of the night. I can go days just talking to myself, and sometimes I bring my work home with me."

That caused Sherlock to sputter, "What? Where the _hell_ did that come from?"

"Flatmates should know the worst things about each other." John steepled his fingers, watching Sherlock over top of them, "Since we were on the subject of flatmates. And since I know that you're a recovering, and highly functioning, cocaine addict, I can predict what your worst traits."

It took a lot of Sherlock's control to keep from snapping again, "And _what_ would that be, good doctor?"

"We'll you've already shown moodiness and signs of agitation. Granted that is also in joint with the nature of your job in recent weeks." The doctor nodded, "There is also the risk of relapse, but what better person to avoid _that_ possible venture than a doctor?" He chuckled lightly, "That, and you would get the independence you want from your brother."

Sherlock sighed, walking to the chair across from the doctor, sitting down, "Alright, I give up. _How _did you know everything? Lestrade swears he didn't tell you about me—"

"He didn't."

"But you still knew that I was a Detective Inspector, and that I was staying on my brother's couch."

"I also know that you are not an "old friend" of Lestrade's, but rather his brother in law."

Sherlock groaned, "_How…_"

John chuckled softly, "Your reaction when I mentioned Lestrade's love life, especially the more graphic nature of it. You seemed horrified, but you didn't flinch away from Lestrade, so you were more disgusted at the image than Lestrade himself. So his partner is someone you know well, but don't necessarily want to see in a sexual manner. So either father or brother. And while Lestrade has grey hair, he isn't that old. So brother it is."

Well _that _was true. He did not need the image of Mycroft…_ick_.

"Ok, I'm following you so far…" Sherlock nodded, "You got that from my reaction to Lestrade's sex life?"

"That, and you both use the same laundry detergent." John reached out a hand, taking hold of Sherlock's sleeve, "I've always noticed that Lestrade's clothes, while modest in quality, are always well laundered, mostly likely at a high end establishment or through a service." He rubbed the sleeve between his thumb and forefinger, "And you have the same texture and scent on your clothes. So you live together, but since we have already established that you and Lestrade are _not_ lovers, it can be deduced that you both live in the home of your brother, Lestrade's lover, who is very well off. Wealthy and politically connected."

"How do you know that Mycroft is politically connected?" Sherlock blinked, trying to keep up in his mind.

"You told me it had been nine months since you left rehab, and you're already working high profile cases. Someone kept you from being fired, or perhaps kept your addiction a secret." John nodded, letting go of Sherlock's sleeve, "He's also the one who gave you your phone."

Before Sherlock could open his mouth to ask, John pressed a finger to his lips, "I'll tell you how, just you wait." With his free hand, John reached into Sherlock's jacket pocket, withdrawing his phone, "This phone isn't on the market yet. Very expensive, top of the line. Not the phone of a DI, and even if you had the money, you wouldn't spend it on a phone, all you need in a phone is a good keyboard." John flipped open the phone to reveal the worn keyboard, "A texter, like myself. Why talk when you can text?" He snapped the phone shut, placing it on the coffee table, "But like I said, if you had the money for a phone like this, you'd be putting it to your own flat.

"And now we get to the fact you're sleeping on your brother's couch. I could _tell_" He added, at Sherlock's confused look, "by the stiffness through your right half of your body. Sleeping somewhere not designed for sleeping. And considering the fact your brother is well off enough to house both you and Lestrade, it would go without saying that he would have a guestroom, maybe even two, and yet you sleep on the couch." John nodded slowly, "Now that tells me that, while your brother has been looking out for you, you resent that you _needed_ looking after. You refused to move into a guest room because you refused to accept a more permanent setting under your brother's wing. Thus, you desire independence, to _prove_ that you do not need looking after. What better way than finding your own place and a flatmate?"

There was silence for a few moments as John and Sherlock just stared at each other, Sherlock's mind was rapidly trying to catch up with what had just been spoken.

"You can ask questions now."

Sherlock blinked, watching the doctor in front of him, "_Fantastic…"_

It took him half a moment to realize he had spoken against John's finger, still pressed against his lips.

John, for his part, looked amused, "That's not the typical response, but most definitely preferable to the usual."

Sherlock smiled softly, "And what would that be?"

"They always assume I'm a shrink, or a profiler, as if there was no difference between one doctorate and another." John sighed, leaning back in his chair. "Or they tell me to go to hell."

That comment made Sherlock chuckled, relaxing a bit, "So…exercising when you think?"

John nodded, getting up from his chair, "Yes, the endorphins aid in my thinking process." The doctor made his way to the kitchen. Sherlock could hear him opening cupboards and toying with the stove, but didn't turn to look at him. "It's a habit I picked up in the army."

"A military doctor…" Sherlock chuckled.

"But you already knew that."

_Right, again_. "I found your website, _The Science of Deduction_."

"Of course you did." Water was running now, John was filling a kettle now, "You're a detective, Sherlock. You were not going to meet with someone about a case without making sure they were credible. And while you trust Lestrade's judgment, you like seeing things for yourself. At least I would hope you did your research on me. I would hate to make the gross mistake of overestimating you."

"You didn't." Sherlock shook his head, "Your website, it's…brilliant, for want of a better word. I can see why Lestrade asks for your help from time to time."

"Mhm…" The sound of a whistling kettle filled the air, followed by pouring. "Not scared off then?"

"I've dealt with worse." Sherlock admitted, "Your…vivid experiments of the human body aren't that bad."

John chuckled, "We shall see about that, Sherlock." A tea cup was placed under Sherlock's nose as John leaned over him, "I take it you take your tea the same way you take your coffee: black, two sugars?"

Blinking, Sherlock grasped the cup carefully, "Thank you, John. You didn't need to do that…"

"You needed the caffeine." John replied simply, carrying his own cup of tea as he returned to his seat. He didn't drink from his cup for a few moments, simply watching Sherlock drink in silence.

Feeling the doctor's gaze, Sherlock cleared his throat, "So, the case…"

"Yes, that is why we're here…for now, at least." John chuckled, "You can let go of the case file, Sherlock, I promise not to bite."

But before Sherlock could pass the case file to John, his phone began to ring. He had nearly forgotten it in the middle of John's deductions, "I better get that…" he muttered, grabbing the phone from the table holding it to his ear, "Holmes."

_"Sir."_

It was Donovan. Sherlock sighed. Donovan never called unless it was work related. "Yeah?"

_"There's been another one."_

He could _feel_ his stomach drop out to the floor, "Where?"

_"Brixton, Lauriston Gardens. And there's a note this time."_

"I'm on my way." Sherlock hung up, getting to his feet, "I'm sorry about this John, but I have to go."

"Of course, there's been another death Why else would you blanche like that?" John nodded, sipping his tea before setting it down, "…anything new?"

There was something in the doctor's voice Sherlock hadn't heard before. "A note…" Sherlock blinked. Curiosity, that's what it was. And John's hand, a _doctor's _hand, was twitching slightly, "…you're actually excited, aren't you?"

"Serial suicides that can't actually be suicides, and now a note?" John grinned, honest to god _grinned, _"What's not to be excited for? Now tell me how you knew."

Again, Sherlock stared at the doctor, unsure what he was hearing, "You were fidgeting. And your voice got higher, kind of..."

John stood slowly, "Good show, there's hope for you yet, Detective Inspector." He chuckled, "Next time, I won't be so obvious."

Before Sherlock could respond, John was already walking out down the stairs, "Come along, Sherlock. There's a lovely crime scene waiting for us!"

There was a brief moment when Sherlock wondered when the _hell_ he invited John to the crime scene. Then he realized, deep down, that he had invited John the moment he and Lestrade had walked into the lab.

"I'm coming John. We'll take my car." He called out, rushing to catch up with the doctor at the foot of the stairs.

* * *

_There it is, the new chapter! Next up, dead body time! Yes, I gave Sherlock a car because it would seem silly if he couldn't drive himself to crime scenes._

_How do you think Donovan and Anderson will react to John? How will he react to them? Will Mycroft make an appearance? Will Sherlock be able to catch his breath?_

_Let me know what you think!_


End file.
